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Tuesday, August 8, 2017

Record Dry Streak About to Be Set in One of America's Notoriously Rainy Cities

Chris Dolce
Published: August 8,2017
The Pacific Northwest has been an epicenter of weather extremes so far in 2017, and yet another record is about to be surpassed in the region this week.
Seattle had not observed measurable rain – 0.01 inches or greater –
in 51 days through Monday. After Tuesday comes to a close, this stretch
with no measurable rain will surpass the current record of 51 days set July 7-Aug. 26, 1951.(MORE: Is Seattle Rainy Reputation Deserved?)
We must note that during this streak of dry weather that a trace of
rain has been observed on four separate days, but that doesn't qualify
as a measurable rain in weather records. Typically a trace of a rain is
the result of sprinkles, drizzle or a brief period of light rain.
Dry weather is fairly common during summer in the Pacific Northwest as the storm track shifts northward. Seattle averages less than an inch of rain in July and August, and June doesn't see much more at 1.57 inches.
But since late June, the overall weather pattern has prevented any
significant rain from entering the Northwest. July 2017 marked only the
seventh time since 1894 that no measurable rain occurred in the Emerald
City during that month. Smoke has been a more common occurrence than any
hints of rain drops to begin August.(MORE: Smoke Leads to Red Sunrises and Sunsets)

The
dominant red and orange shaded areas represent high pressure in the
upper atmosphere that engulfed the Northwest in July, resulting in
extended dry weather.

The orange and red bulls-eye over the northwestern states on the map
at right illustrates where an area of high pressure has been dominant in
the heart of this dry stretch. That high-pressure system prevented any
potential Pacific Ocean weather systems from nudging their way into the
Pacific Northwest.
The dryness in Seattle
this summer is quite a flip from the opposite extreme we were tracking
in the winter and spring when it was excessively wet and cloudy.
As of July 31, Sea-Tac airport was in the midst of its second-wettest year to date,
according to the Southeast Regional Climate Center. That high ranking
even includes the aforementioned month of July that had no measurable
rain.
Sea-Tac airport managed a total of five sunny days – defined as a
daily average sky cover of 30 percent or less – from Jan. 1 through
April 30. Four of those days occurred in January and the other in
February, the day before Valentine's Day.(MORE: Rainy-Season Records Smashed in Seattle)
Yes, that means there were no sunny days in March or April. Conditions improved in May when five sunny days were recorded.
There were periods of sunshine here and there, despite this meager sunny-day statistic.
Seattle's reputation for being notoriously wet is mainly due to the fall, winter and spring months.

Average annual precipitation in Seattle
is about 37 inches, which as a comparison, is less than Atlanta's
average of about 49 inches. It's the persistence of the wet and dreary
conditions that makes Seattle stand out when it comes to being wet.
Seattle experiences an average of 152 rainy days a year, which is more than most cities across the U.S.

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